Polycrystalline diamond materials, along with ceramic carbides such as silicon carbide, tungsten carbide, and boron carbide, are among the hardest materials known. Fine grained bodies made by compacting and sintering or hot pressing particles of these compositions are widely used for cutting tools, as in turning and milling; in grinding, sawing, drilling and dressing; and in other applications such as in armour. Their great hardness notwithstanding, however, such sintered bodies are relatively brittle and tend to crack and fracture more readily than some other materials which are not as hard.
There has therefore been a need for a "tougher" form of such ultrahard materials, which can better resist fracture by cracking.